1. Field of the Invention
The present invention relates generally to container security and, more particularly, to a shipping container security system, and to the communication sub-systems used in this system.
2. Background of the Invention
In today's security conscious transportation environment, there is a strong need to cost-effectively and accurately monitor the contents of containerized shipments. This need exists both in the United States and abroad.
Despite the strong need, until recently few solutions, if any, have been able to provide the protection and accuracy needed to suit the transportation industry and the government agencies charged with monitoring shipments. This lack of an acceptable solution is due to many factors which complicate interstate and international shipping. Shipping containers are used to transport most of the commerce entering, leaving, and transiting or moving within the United States. It is estimated that there are over 6 million containers moving in global commerce. Shipping containers have revolutionized the transportation of goods by greatly reducing the number of times goods must be loaded and unloaded during transport. However, at the same time, this same advantage has created a major problem in that it is very difficult to monitor and track the contents of each container during transport.
Beyond their basic construction, monitoring the content of shipping containers is also difficult because these containers are carried through numerous transit points and depots all over the world and it is impractical to stop and check the contents of each container individually at each point of transit. Dealing with this problem, the U.S. Customs Service estimates it can inspect just 5% of the 6 million containers entering and reentering the U.S. each year. Accordingly, agencies such as the United States Customs Service are seeking improved ways to achieve cargo container security and integrity upon arrival at the ports of entry of the United States.
To date, many government agencies have initiated programs to improve container security. These include many useful elements that are intended to preclude their use by terrorists. However, at present, none of the container tracking systems in use provides a way to assure the integrity of the contents of the containers to assure global container security. Current computer tracking systems are effective at monitoring the location of individual containers from point of origin to destination and maintaining an inventory of loaded and empty containers.
Many of these systems rely on communications devices mounted on or inside the containers that have external antenna elements which send messages regarding the status of the container and contents to satellites or ground stations, from which the messages are rerouted to shipping companies, freight forwarders, and companies through a central monitoring station. Some of these systems contain multiple modes of communication for various purposes including, short range wireless such as Bluetooth or 802.11 WiFi, cellular, or satellite connections. While the short range wireless is often used with the container, the cellular and satellite are required to communicate critical information about the status and contents of the container to the outside world and require antennas. Since the containers are almost universally constructed out of corrugated steel, signals transmitted through antennas on the interior of the container may have significant radio frequency path loss as much of the transmitted energy would be absorbed by the container walls. As a result, virtually all of these systems need to have some variation of external antenna device. However this is also problematic, in that it is often difficult to cable from a communications device located on the interior of the container with sensor to an antenna location on the exterior of the container. Also, for satellite communication the ideal location for the antenna is often on the container roof, but as containers are stacked the antennas may easily get damaged or crushed. The proper operation of the communications devices of these systems is critical, and when it is not possible to communicate, the entire functionality of the system is compromised. Conventional antennas mounted on the exterior of containers may have multiple disadvantages, in that they: may interfere with normal container handling process; may be damaged when containers are stacked or moved; may become detached during the container handling process; may appear obvious to the casual observer which may not be desirable for discreet monitoring of containers; and may be easily defeated by a person or persons who wish to interfere with a container monitoring system for subversive purposes.
For these reasons, it is desirable to have an antenna system that can be integrated into the top or side of container wall itself. A system such as this would have multiple advantages including: avoiding change in current methods of container handling; difficult or impossible to detach or damage; hidden from view as it looks like all other containers; no field installation of an external antenna; and lower cost than separate antenna systems.
The invention described herein, provides an alternative safe, and reliable, and cost effective alternative antenna system which is actually integrated into the container roof or wall.